Funds are requested to purchase a liquid chromatograph - triple quadrupole - mass spectrometer (LC-TQ MS) Waters Quattro micro API Tandem Quadrupole System) for use as a shared instrument by researchers of the Medical College of Wisconsin. The College has 950 faculty and NIH funding but has no shared LC-MS/MS instrumentation. This instrument is critical for future research. During the past 11 years, the Mass Spectrometry Shared Facility of the Department of Pharmacology and Toxicology has provided mass spectrometry expertise and instrumentation to the faculty of the College. The Facility has established protocols for handling samples from multiple users and dealing with samples with different chemical characteristics. It has a Hewlett - Packard gas chromatograph - single quadrupole mass spectrometer (Engine) and an Agilent liquid chromatograph - single quadrupole mass spectrometer (LC-MSD). The LC-MSD is currently widely used by a number of investigators for analysis of lipids, steroid hormones, peptides and proteins. These varied needs have created an increasing demand for LC-MS analysis. Therefore, we request the purchase of a LC-TQ MS because of its MS/MS capabilities that will overcome many of the limitations of the current instrument. This MS/MS capability will facilitate the identification of unknown compounds. This function is currently performed by GC-MS, which requires sample derivatization and compatibility with GC conditions. The LC-TQ MS will also facilitate the measurement of analytes with the same m/z since daughter ions of different m/z may be selected for measurement. This will result in increase in confidence in analysis of certain peaks in complex samples. It will also result in shorter run time since the LC-MSD needs a complete resolution of multiple compounds with same m/z. The needs of the 15 principal users of this grant fall into four categories: (1) identification and measurement of eicosanoids, (2) measurement of lipid peroxidation products, isoprostanes and oxylipids, (3) analysis of addictive drugs and their metabolites, and (4) miscellaneous applications. About 75-80% of instrument time will be available to these participants and the remaining time will be available to other investigators at the College. [unreadable] [unreadable]